The conventional rodless cylinder described in Patent Document 1 cited below is known. This rodless cylinder includes a cylinder tube (tube) having a longitudinal slit, and a moving unit adapted to move along the slit. The moving unit has an inner tube portion and an outer slit portion, and is moved with the inner tube portion being pressed by the fluid.
This conventional rodless cylinder further includes an inner seal band extended along the slit to close the slit from inside the inner hole of the tube. The longitudinal ends of the inner seal band are restricted, and the intermediate portion of the inner seal band is passed through a passage groove formed on the inner tube portion. As a result, the fluid can act on the inner tube portion without leaking in spite of the presence of the slit. This rodless cylinder has a wear-resistant thin-plate slide contact member of synthetic resin on each side of the passage groove, so that the transverse (crosswise) displacement of the inner seal band is prevented. Thus, the situation, in which the inner seal band is displaced to release the fluid, is prevented from occurring.